Impact: fix potential (non-x86) SMP boot failure with some gcc versions
The deprecated cpu_*_map are currently #defined to the new cpu_*_mask,
except without the const. Some versions of gcc seem to dislike this,
and I suspect this will break boot for some archs with the "wrong" gcc
version.
So play it safe and use real vars until we kill them all (replacements
are init_*_map(), set_cpu_*() and cpu_*_mask).
PowerPC and Alpha have reported warnings, and James Bottomley
encountered worse: gcc was simply not changing cpu_possible_map,
causing boot failure (fixed by using init_cpu_possible()).
See also:
Alpha gcc 4.2 warning fix:
ee0c468bb151aad23281660152d2894f1e214238
Voyager bug report:
lkml: [PATCH] voyager: fix cpu bootmaps
Message-Id: <1233340317.3248.39.ca...@localhost.localdomain>
(Merged without comments in 92ab78315c638515d0e81b0c70b2082f713582d9)
Signed-off-by: Rusty Russell <ru...@rustcorp.com.au>
Cc: linuxppc-dev@ozlabs.org
Cc: Ivan Kokshaysky <i...@jurassic.park.msu.ru>
Cc: james.bottom...@hansenpartnership.com
Cc: Mike Travis <tra...@sgi.com>
---
include/linux/cpumask.h | 14 +++++++++-----
kernel/cpu.c | 10 ++++++++++
2 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -487,11 +487,15 @@ extern const struct cpumask *const cpu_p
extern const struct cpumask *const cpu_present_mask;
extern const struct cpumask *const cpu_active_mask;
-/* These strip const, as traditionally they weren't const. */
-#define cpu_possible_map (*(cpumask_t *)cpu_possible_mask)
-#define cpu_online_map (*(cpumask_t *)cpu_online_mask)
-#define cpu_present_map (*(cpumask_t *)cpu_present_mask)
-#define cpu_active_map (*(cpumask_t *)cpu_active_mask)
+/* Deprecated: use cpu_*_mask and set_cpu_*(). */
+#define cpu_possible_map (*_cpu_possible_mask_nonconst)
+#define cpu_online_map (*_cpu_online_mask_nonconst)
+#define cpu_present_map (*_cpu_present_mask_nonconst)
+#define cpu_active_map (*_cpu_active_mask_nonconst)
+extern struct cpumask *_cpu_possible_mask_nonconst;
+extern struct cpumask *_cpu_online_mask_nonconst;
+extern struct cpumask *_cpu_present_mask_nonconst;
+extern struct cpumask *_cpu_active_mask_nonconst;
#if NR_CPUS > 1
#define num_online_cpus() cpumask_weight(cpu_online_mask)
diff --git a/kernel/cpu.c b/kernel/cpu.c
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -565,3 +565,13 @@ void init_cpu_online(const struct cpumas
{
cpumask_copy(to_cpumask(cpu_online_bits), src);
}
+
+/* Deprecated accessors. */
+struct cpumask *_cpu_possible_mask_nonconst = to_cpumask(cpu_possible_bits);
+EXPORT_SYMBOL(_cpu_possible_mask_nonconst);
+struct cpumask *_cpu_online_mask_nonconst = to_cpumask(cpu_online_bits);
+EXPORT_SYMBOL(_cpu_online_mask_nonconst);
+struct cpumask *_cpu_present_mask_nonconst = to_cpumask(cpu_present_bits);
+EXPORT_SYMBOL(_cpu_present_mask_nonconst);
+struct cpumask *_cpu_active_mask_nonconst = to_cpumask(cpu_active_bits);
+EXPORT_SYMBOL(_cpu_active_mask_nonconst);
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